Process for hydrotreating a coal tar stream

ABSTRACT

A process for hydrotreating a coal tar stream is described. A coal tar stream is provided, and the coal tar stream is fractionated into at least a light naphtha range hydrocarbon stream having a boiling point in the range of about 85° C. (185° F.) to about 137.8° C. (280° F.). The light naphtha range hydrocarbon stream is hydrotreated by contacting the light naphtha range hydrocarbon stream with a naphtha hydrotreating catalyst.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No. 61/906,003 filed on Nov. 19, 2013, the entirety of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

Many different types of chemicals are produced from the processing of petroleum. However, petroleum is becoming more expensive because of increased demand in recent decades.

Therefore, attempts have been made to provide alternative sources for the starting materials for manufacturing chemicals. Attention is now being focused on producing liquid hydrocarbons from solid carbonaceous materials, such as coal, which is available in large quantities in countries such as the United States and China.

Pyrolysis of coal produces coke and coal tar. The coke-making or “coking” process consists of heating the material in closed vessels in the absence of oxygen to very high temperatures. Coke is a porous but hard residue that is mostly carbon and inorganic ash, which may be used in making steel.

Coal tar is the volatile material that is driven off during heating, and it comprises a mixture of a number of hydrocarbon compounds. It can be separated to yield a variety of organic compounds, such as benzene, toluene, xylene, naphthalene, anthracene, and phenanthrene. These organic compounds can be used to make numerous products, for example, dyes, drugs, explosives, flavorings, perfumes, preservatives, synthetic resins, and paints and stains. The residual pitch left from the separation is used for paving, roofing, waterproofing, and insulation.

Coal tar includes many contaminants that make it unsuitable for certain end products. Because of increasingly stringent standards, it is imperative to provide ways to treat coal tar to remove contaminants.

There is a need for an improved process for removing contaminants from coal.

SUMMARY OF THE INVENTION

One aspect of the invention involves a process for hydrotreating a coal tar stream. A coal tar stream is provided, and the coal tar stream is fractionated into at least a light naphtha range hydrocarbon stream having a boiling point in the range of about 85° C. (185° F.) to about 137.8° C. (280° F.). The light naphtha range hydrocarbon stream is hydrotreated by contacting the light naphtha range hydrocarbon stream with a naphtha hydrotreating catalyst.

Another aspect of the invention involves a process for providing a light hydrocarbon stream. A coal tar feed is pyrolyzed into at least a coke stream and a coal tar stream. The coal tar stream has a boiling point greater than about 400° C. The coal tar stream is hydrotreated by contacting the light hydrocarbon stream with a naphtha hydrotreating catalyst. The hydrotreated stream is fractionated to provide at least one light hydrocarbon stream.

Another aspect of the invention involves a process for hydrotreating a coal tar stream. A coal feed is pyrolyzed into at least a coke stream and a coal tar stream in a pyrolysis zone. The coal tar stream has a boiling point greater than about 400° C. The coal tar stream is contacted with a solvent in a solvent extraction zone to provide a heavy insoluble fraction and a light soluble fraction. The heavy insoluble fraction is separated from the light soluble fraction. The heavy insoluble fraction is hydrotreated by contacting the heavy insoluble fraction with a kerosene or distillate hydrotreating catalyst at a temperature of between about 550° C. and about 700° C. and at a pressure of between about 4.8 MPa (700 psi) and about 8.3 MPa, (1200 psi).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a first embodiment of the process of the present invention.

FIG. 2 is an illustration of a second embodiment of the process of the present invention.

FIG. 3 is an illustration of a third embodiment of the process of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a first embodiment of the process 5. A coal feed 10 can be sent to a pyrolysis zone 15, such as a coking oven. Alternatively or additionally, a portion of the coal feed 10 can be sent to a gasification zone (not shown). In the pyrolysis zone 15, the coal is heated at high temperature, e.g., up to about 2,000° C. (3,600° F.), in the absence of oxygen to drive off the volatile components. Coking produces a coke stream 20 and a coal tar stream 25. The coke stream 20 can be used in other processes, such as the manufacture of steel.

The coal tar stream 25 obtained from the pyrolysis zone 15, or from other sources, is separated in fractionation zone 30. Coal tar comprises a complex mixture of heterocyclic aromatic compounds and their derivatives with a wide range of boiling points. The number of fractions and the components in the various fractions can be varied as is well known in the art. A typical separation process involves separating the coal tar into four to six streams. For example, there can be a fraction comprising NH₃, CO, and light hydrocarbons, a light oil fraction with boiling points between 0° C. and 180° C., a middle oil fraction with boiling points between 180° C. to 230° C., a heavy oil fraction with boiling points between 230 to 270° C., an anthracene oil fraction with boiling points between 270° C. to 350° C., and pitch.

The light oil fraction contains compounds such as benzenes, toluenes, xylenes, naphtha, coumarone-indene, dicyclopentadiene, pyridine, and picolines. The middle oil fraction contains compounds such as phenols, cresols and cresylic acids, xylenols, naphthalene, high boiling tar acids, and high boiling tar bases. The heavy oil fraction contains and creosotes. The anthracene oil fraction contains anthracene. Pitch is the residue of the coal tar distillation containing primarily aromatic hydrocarbons and heterocyclic compounds.

In the process 5 shown in FIG. 1, the coal tar stream 25 is fractionated into at least a light naphtha range hydrocarbon stream 40 having a boiling point in a range of about 85° C. (185° F.) to about 137.8° C. (280° F.). This can be, as one example, the lightest cut from the coal tar stream 25 produced from the pyrolysis zone 15. The fractionation zone 30 can further provide a heavier hydrocarbon stream or streams 45, a fraction 35 comprising NH₃, CO, H₂S, and light hydrocarbons, and a pitch stream 50. The light naphtha range hydrocarbon stream 40 can include a hexane insoluble stream, a benzene insoluble stream, or both, but this is not required in all processes.

The light naphtha range hydrocarbon stream 40 is sent to a hydrotreating zone 55, where the light naphtha range hydrocarbon stream is hydrotreated. Hydrotreating is a process in which hydrogen gas is contacted with the hydrocarbon stream 40 in the presence of suitable catalysts which are primarily active for the removal of heteroatoms, such as sulfur, nitrogen, and metals from the hydrocarbon feedstock. In hydrotreating, hydrocarbons with double and triple bonds may be saturated. Aromatics may also be saturated.

Typical hydrotreating reaction conditions include a temperature of about 290° C. (550° F.) to about 455° C. (850° F.), a pressure of about 3.4 MPa (500 psig) to about 26.7 MPa (4,000 psig), a liquid hourly space velocity of about 0.5 hr⁻¹ to about 4 hr⁻¹, and a hydrogen rate of about 168 to about 1,011 Nm³/m³ oil (1,000 to 6,000 scf/bbl). Preferably, the light naphtha range hydrocarbon stream 45 is hydrotreated under conditions such that cracking does not take place.

Typical hydrotreating catalysts include at least one Group VIII metal, preferably iron, cobalt and nickel, and at least one Group VI metal, preferably molybdenum and tungsten, on a high surface area support material, preferably alumina. Other typical hydrotreating catalysts include zeolitic catalysts, as well as noble metal catalysts where the noble metal is selected from palladium and platinum. Preferably, the naphtha hydrotreating catalyst includes molybdenum and either cobalt, nickel, or a combination of cobalt and nickel. A particular example hydrotreating catalyst is nickel and molybdenum. Preferably, the hydrotreating removes sulfur to provide a hydrotreated stream 60 having a sulfur concentration of less than about 0.2 ppm, which is useful for downstream processes.

The hydrotreated stream 60 may be blended with a gasoline stream. Alternatively, the hydrotreated stream 60 can be fed to a processing zone 65 for providing one or more products 70. For example, the hydrotreated stream 60 can be reformed to provide an aromatics stream. Reforming is a catalytic process for producing aromatics from paraffins and naphthenes by rearranging or restructuring hydrocarbon molecules and breaking larger hydrocarbon molecules into smaller ones. Hydrogen is produced as a byproduct. An example reforming process is the CCR PLATFORMING™ catalytic reforming process (UOP, Des Plaines, Ill.), which includes dehydrogenation of naphthenes, isomerization of paraffins and naphthenes, dehydrogenation of paraffins, paraffin hydrocracking, and dealkylation of aromatics. Typical reaction conditions include operating pressures from about 345 to about 4,830 kPa, and reactor weighted-average inlet temperatures (WAIT) between about 490° C. to about 540° C. Liquid hourly space velocity (LHSV) can vary, and the LHSV and reaction temperature can be configured to produce a particular octane product. An example reforming process includes a catalyst that is continuously regenerated in a regeneration section.

As other examples, the hydrotreated stream 60 can undergo conversion by hydrocracking, fluid catalytic cracking, alkylation, transalkylation, oxidation, or hydrogenation.

Hydrocracking is a process in which hydrocarbons crack in the presence of hydrogen to lower molecular weight hydrocarbons. Typical hydrocracking conditions may include a temperature of about 290° C. (550° F.) to about 468° C. (875° F.), a pressure of about 3.5 MPa (500 psig) to about 20.7 MPa (3,000 psig), a liquid hourly space velocity (LHSV) of about 1.0 to less than about 2.5 hr⁻¹, and a hydrogen rate of about 421 to about 2,527 Nm³/m³ oil (2,500 to 15,000 scf/bbl). Typical hydrocracking catalysts include amorphous silica-alumina bases or low-level zeolite bases combined with one or more Group VIII or Group VIB metal hydrogenating components, or a crystalline zeolite cracking base upon which is deposited a Group VIII metal hydrogenating component. Additional hydrogenating components may be selected from Group VIB for incorporation with the zeolite base.

Fluid catalytic cracking (FCC) is a catalytic hydrocarbon conversion process accomplished by contacting heavier hydrocarbons in a fluidized reaction zone with a catalytic particulate material. The reaction in catalytic cracking is carried out in the absence of substantial added hydrogen or the consumption of hydrogen. The process typically employs a powdered catalyst having the particles suspended in a rising flow of feed hydrocarbons to form a fluidized bed. In representative processes, cracking takes place in a riser, which is a vertical or upward sloped pipe. Typically, a pre-heated feed is sprayed into the base of the riser via feed nozzles where it contacts hot fluidized catalyst and is vaporized on contact with the catalyst, and the cracking occurs converting the high molecular weight oil into lighter components including liquefied petroleum gas (LPG), gasoline, and a distillate. The catalyst-feed mixture flows upward through the riser for a short period (a few seconds), and then the mixture is separated in cyclones. The hydrocarbons are directed to a fractionator for separation into LPG, gasoline, diesel, kerosene, jet fuel, and other possible fractions. While going through the riser, the cracking catalyst is deactivated because the process is accompanied by formation of coke which deposits on the catalyst particles. Contaminated catalyst is separated from the cracked hydrocarbon vapors and is further treated with steam to remove hydrocarbon remaining in the pores of the catalyst. The catalyst is then directed into a regenerator where the coke is burned off the surface of the catalyst particles, thus restoring the catalyst's activity and providing the necessary heat for the next reaction cycle. The process of cracking is endothermic. The regenerated catalyst is then used in the new cycle. Typical FCC conditions include a temperature of about 400° C. to about 800° C., a pressure of about 0 to about 688 kPag (about 0 to 100 psig), and contact times of about 0.1 seconds to about 1 hour. The conditions are determined based on the hydrocarbon feedstock being cracked, and the cracked products desired. Zeolite-based catalysts are commonly used in FCC reactors, as are composite catalysts which contain zeolites, silica-aluminas, alumina, and other binders.

Alkylation is typically used to combine light olefins, for example mixtures of alkenes such as propylene and butylene, with isobutane to produce a relatively high-octane branched-chain paraffinic hydrocarbon fuel, including isoheptane and isooctane. Similarly, an alkylation reaction can be performed using an aromatic compound such as benzene in place of the isobutane. When using benzene, the product resulting from the alkylation reaction is an alkylbenzene (e.g. toluene, xylenes, ethylbenzene, etc.). For isobutane alkylation, typically, the reactants are mixed in the presence of a strong acid catalyst, such as sulfuric acid or hydrofluoric acid. The alkylation reaction is carried out at mild temperatures, and is typically a two-phase reaction. Because the reaction is exothermic, cooling is needed. Depending on the catalyst used, normal refinery cooling water provides sufficient cooling. Alternatively, a chilled cooling medium can be provided to cool the reaction. The catalyst protonates the alkenes to produce reactive carbocations which alkylate the isobutane reactant, thus forming branched chain paraffins from isobutane. Aromatic alkylation is generally now conducted with solid acid catalysts including zeolites or amorphous silica-aluminas.

The alkylation reaction zone is maintained at a pressure sufficient to maintain the reactants in liquid phase. For a hydrofluoric acid catalyst, a general range of operating pressures is from about 200 to about 7,100 kPa absolute. The temperature range covered by this set of conditions is from about −20° C. to about 200° C. For at least alkylation of aromatic compounds, the temperature range is from about 100° C. to about 200° C. at the pressure range of about 200 to about 7,100 kPa.

Transalkylation is a chemical reaction resulting in transfer of an alkyl group from one organic compound to another. Catalysts, particularly zeolite catalysts, are often used to effect the reaction. If desired, the transalkylation catalyst may be metal stabilized using a noble metal or base metal, and may contain suitable binder or matrix material such as inorganic oxides and other suitable materials. In a transalkylation process, a polyalkylaromatic hydrocarbon feed and an aromatic hydrocarbon feed are provided to a transalkylation reaction zone. The feed is usually heated to reaction temperature and then passed through a reaction zone, which may comprise one or more individual reactors. Passage of the combined feed through the reaction zone produces an effluent stream comprising unconverted feed and product monoalkylated hydrocarbons. This effluent is normally cooled and passed to a stripping column in which substantially all C₅ and lighter hydrocarbons present in the effluent are concentrated into an overhead stream and removed from the process. An aromatics-rich stream is recovered as net stripper bottoms, which is referred to as the transalkylation effluent.

The transalkylation reaction can be effected in contact with a catalytic composite in any conventional or otherwise convenient manner and may comprise a batch or continuous type of operation, with a continuous operation being preferred. The transalkylation catalyst is usefully disposed as a fixed bed in a reaction zone of a vertical tubular reactor, with the alkylaromatic feed stock charged through the bed in an upflow or downflow manner. The transalkylation zone normally operates at conditions including a temperature in the range of about 130° C. to about 540° C. The transalkylation zone is typically operated at moderately elevated pressures broadly ranging from about 100 kPa to about 10 MPa absolute. The transalkylation reaction can be effected over a wide range of space velocities. That is, volume of charge per volume of catalyst per hour; weight hourly space velocity (WHSV) generally is in the range of from about 0.1 to about 30 hr⁻¹. The catalyst is typically selected to have relatively high stability at a high activity level.

Oxidation involves the oxidation of hydrocarbons to oxygen-containing compounds, such as aldehydes. The hydrocarbons include alkanes, alkenes, typically with carbon numbers from 2 to 15, and alkyl aromatics, linear, branched, and cyclic alkanes and alkenes can be used. Oxygenates that are not fully oxidized to ketones or carboxylic acids can also be subjected to oxidation processes, as well as sulfur compounds that contain —S—H moieties, thiophene rings, and sulfone groups. The process is carried out by placing an oxidation catalyst in a reaction zone and contacting the feed stream which contains the desired hydrocarbons with the catalyst in the presence of oxygen. The type of reactor which can be used is any type well known in the art such as fixed-bed, moving-bed, multi-tube, CSTR, fluidized bed, etc. The feed stream can be flowed over the catalyst bed either up-flow or down-flow in the liquid, vapor, or mixed phase. In the case of a fluidized-bed, the feed stream can be flowed co-current or counter-current. In a CSTR the feed stream can be continuously added or added batch-wise. The feed stream contains the desired oxidizable species along with oxygen. Oxygen can be introduced either as pure oxygen or as air, or as liquid phase oxidants including hydrogen peroxide, organic peroxides, or peroxy-acids. The molar ratio of oxygen (O₂) to alkane can range from about 5:1 to about 1:10. In addition to oxygen and alkane or alkene, the feed stream can also contain a diluent gas selected form nitrogen, neon, argon, helium, carbon dioxide, steam or mixtures thereof. As stated, the oxygen can be added as air which could also provide a diluent. The molar ratio of diluent gas to oxygen ranges from greater than zero to about 10:1. The catalyst and feed stream are reacted at oxidation conditions which include a temperature of about 300° C. to about 600° C., a pressure of about 101 kPa to about 5,066 kPa and a space velocity of about 100 to about 100,000 hr⁻¹.

Hydrogenation involves the addition of hydrogen to hydrogenatable hydrocarbon compounds. Alternatively hydrogen can be provided in a hydrogen-containing compound with ready available hydrogen, such as tetralin, alcohols, hydrogenated naphthalenes, and others via a transfer hydrogenation process with or without a catalyst. The hydrogenatable hydrocarbon compounds are introduced into a hydrogenation zone and contacted with a hydrogen-rich gaseous phase and a hydrogenation catalyst in order to hydrogenate at least a portion of the hydrogenatable hydrocarbon compounds. The catalytic hydrogenation zone may contain a fixed, ebulated or fluidized catalyst bed. This reaction zone is typically at a pressure from about 689 kPag (100 psig) to about 13,790 kPa gauge (2,000 psig) with a maximum catalyst bed temperature in the range of about 177° C. (350° F.) to about 454° C. (850° F.). The liquid hourly space velocity is typically in the range from about 0.2 hr ⁻¹ to about 10 hr⁻¹ and hydrogen circulation rates from about 200 standard cubic feet per barrel (SCFB) (35.6 m³/m³) to about 10,000 SCFB (1778 m³/m³).

FIG. 2 shows a second embodiment of a process 72 of the present invention, in which like reference characters apply to similar features. In the process of FIG. 2, the coal feed 10 is pyrolyzed in the pyrolysis zone 15 into at least the coke stream 20 and the coal tar stream 25. An example coal tar stream 25 in this embodiment has a boiling point greater than about 400° C. The coal tar stream 25 can also have a molecular weight distribution between about 100 and about 4,000, and preferably a molecular weight distribution between about 250 and about 700.

The coal tar stream 25 is hydrotreated in a hydrotreating zone 75. As with the hydrotreating zone 30 shown in FIG. 1, in the hydrotreating zone 75, the coal tar stream 25 is contacted with a naphtha hydrotreating catalyst. The naphtha hydrotreating catalyst preferably includes molybdenum and either cobalt, nickel, or both cobalt and nickel. Preferably, the naphtha hydrotreating catalyst includes nickel and molybdenum. The hydrotreating in the hydrotreating zone 75 can remove sulfur, nitrogen, or both. The hydrotreating preferably removes sulfur to provide a hydrotreated coal tar stream 80 having a sulfur concentration of less than about 0.2 ppm. Hydrotreating conditions can be similar to those disclosed above.

The hydrotreated coal tar stream 80 is fractionated in fractionation zone 85 to provide at least one light hydrocarbon stream 95. Preferably, this light hydrocarbon stream 95 is a light naphtha range hydrocarbon stream having a boiling point in a range of about 85° C. (185° F.) to about 137.8° C. (280° F.). The fractionation zone 85 can also produce other hydrocarbon streams such as a middle oil fraction 100 with boiling points between 180° C. to 230° C., a heavy oil fraction 105 with boiling points between 230° C. to 270° C., an anthracene oil fraction (not shown) with boiling points between 270° C. to 350° C., and a pitch stream 110. A fraction 90 comprising NH₃, CO, H₂S, and light hydrocarbons can also be provided by the fractionation zone 85. One or more of the hydrocarbon streams, such as the light hydrocarbon stream 95 as shown in FIG. 2, or other hydrocarbon streams can be fed to a processing zone 115 as described above to produce one or more products 120.

FIG. 3 shows a third embodiment of the process 128 of the present invention, where like reference characters refer to similar features. The coal stream 10 is pyrolyzed in the pyrolysis zone 15 into at least the coke stream 20 and the coal tar stream 25. Preferably, the coal tar stream 25 has a boiling point greater than about 400° C. Further, the coal tar stream 25 can have a molecular weight distribution between about 100 and about 4000. Preferably, the coal tar stream 25 has a molecular weight distribution between about 250 and about 700. The coal tar stream 25 enters a solvent extraction zone 130. A solvent 135, which preferably comprises a hydrocarbon fraction, and more preferably comprises benzene, hexane, or a combination, is fed to the solvent extraction zone 130. Solvent extraction conditions include a device allowing for intense contacting of the coal tar stream 25 and the solvent 135, at temperatures and pressures where both streams are in the liquid phase and are unlikely to react or degrade. An output stream 140 of the solvent extraction zone 130 is fed to a separation zone 145, such as a settling vessel, where the light soluble and heavy insoluble fractions can be separated due to the difference in their specific density. The separation zone 145 separates a light soluble fraction 150 from a heavy insoluble fraction 155. The light soluble fraction 150 can be processed using any of the processes disclosed elsewhere herein.

The heavy insoluble fraction 155 is fed into a hydrotreating zone 160. In the hydrotreating zone 160, the heavy insoluble fraction 155 is contacted with either a kerosene or distillate hydrotreating catalyst for hydrotreatment. Example kerosene or distillate hydrotreating catalysts include Co/Mo/Alumina and Ni/Mo/Alumina of a type that is traditionally used in this service. Example conditions for the hydrotreating zone 160 include a temperature of between about 550° C. and about 700° C., and a pressure of between about 4.8 MPa (700 psi) and about 8.3 MPa (1200 psi). The hydrotreated heavy insoluble fraction 165 can be fed to a processing zone 170 for further processing, including any of the downstream processes described elsewhere herein, to provide one or more products 175.

While at least one exemplary embodiment has been presented in the foregoing detailed description of the invention, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention. It being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims. 

What is claimed is:
 1. A process comprising: providing a coal tar stream; fractionating the coal tar stream into at least a light naphtha range hydrocarbon stream having a boiling point in a range of about 85° C. (185° F.) to about 137.8° C. (280° F.); and hydrotreating the light naphtha range hydrocarbon stream by contacting the light naphtha range hydrocarbon stream with a naphtha hydrotreating catalyst.
 2. The process of claim 1 wherein hydrotreating the light naphtha range hydrocarbon stream removes sulfur, nitrogen, or both.
 3. The process of claim 1 wherein hydrotreating the light naphtha range hydrocarbon stream removes sulfur to provide a hydrotreated stream having a sulfur concentration of less than about 0.2 ppm.
 4. The process of claim 1 wherein the naphtha hydrotreating catalyst comprises molybdenum and one or more of cobalt and nickel.
 5. The process of claim 1 wherein the naphtha hydrotreating catalyst comprises nickel and molybdenum.
 6. The process of claim 1 wherein the light naphtha range hydrocarbon stream comprises a hexane insoluble stream, a benzene insoluble stream, or both.
 7. The process of claim 1 further comprising: blending the hydrotreated stream with a gasoline stream.
 8. The process of claim 1 further comprising: reforming the hydrotreated stream to provide an aromatics stream.
 9. The process of claim 1 wherein providing a coal tar stream comprises pyrolyzing a coal feed in a pyrolysis zone to provide the coal tar stream and a coke stream.
 10. A process comprising: pyrolyzing a coal feed into at least a coke stream and a coal tar stream in a pyrolysis zone, the coal tar stream having a boiling point greater than about 400 C; hydrotreating the coal tar stream by contacting the coal tar stream with a naphtha hydrotreating catalyst; and fractionating the hydrotreated stream to provide at least one light hydrocarbon stream.
 11. The process of claim 10 wherein the coal tar stream has a molecular weight distribution between about 100 and about 4,000.
 12. The process of claim 10 wherein the coal tar stream has a molecular weight distribution between about 250 and about
 700. 13. The process of claim 10 wherein hydrotreating the coal tar stream removes sulfur, nitrogen, or both.
 14. The process of claim 10 wherein hydrotreating the coal tar stream removes sulfur to provide a hydrotreated stream having a sulfur concentration of less than about 0.2 ppm.
 15. The process of claim 10 wherein the naphtha hydrotreating catalyst comprises nickel and molybdenum.
 16. A process comprising: pyrolyzing a coal feed into at least a coke stream and a coal tar stream in a pyrolysis zone, the coal tar stream having a boiling point greater than about 400° C.; contacting the coal tar stream with a solvent in a solvent extraction zone to provide a heavy insoluble fraction and a light soluble fraction; separating the heavy insoluble fraction from the light soluble fraction; and hydrotreating the heavy insoluble fraction by contacting the heavy insoluble fraction with a kerosene or distillate hydrotreating catalyst at a temperature of between about 550° C. and about 700° C. and at a pressure of between about 4.8 MPa (700 psi) and about 8.3 MPa (1,200 psi).
 17. The process of claim 16 wherein the coal tar stream has a molecular weight distribution between about 100 and about
 4000. 18. The process of claim 16 wherein the coal tar stream has a molecular weight distribution between about 250 and about
 700. 19. The process of claim 17 wherein the solvent is a hydrocarbon fraction.
 20. The process of claim 19 wherein the solvent is selected from the group consisting of benzene and hexane. 